dealer installed rear speaker b-body

I need to see a dealer installed speaker for the rear seat. This could be any that does not use the slotted rear deck cover. wmaybe someone could tell me about the cover and if it is round or square. Does the speaker bolt from the bottom up or from the top down? Thanks

Hope,this helps only pic available in dealer parts manual.good thru 68.

Yup, That helped with the shape. Thanks